Question: Simplify the following expression: $a = \dfrac{-5z - 2}{2z} \div \dfrac{1}{4}$
Dividing by a number is the same as multiplying by its inverse. $a = \dfrac{-5z - 2}{2z} \times \dfrac{4}{1}$ When multiplying fractions, we multiply the numerators and the denominators. $a = \dfrac{(-5z - 2) \times 4} {(2z) \times 1}$ $a = \dfrac{-20z - 8}{2z}$ Simplify: $a = \dfrac{-10z - 4}{z}$